Chelatable spiro [benzopyran-2, 2&#39;-indoline] derivatives



3,299,079 CHELATABLE SPIRO [BENZOPYRAN-2,2'-

INDOLINE] DERIVATIVES Lloyd D. Taylor, Everett, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware No Drawing. Filed Mar. 11, 1966, Ser. No. 533,406

4 Claims. (Cl. 260294.7)

This application is in part a continuation of Serial No. 302,010, filed August 14, 196-3, now abandoned;

This invention relates to a novel class of chemical compounds which will undergo color changes upon exposure to heat or light of various wavelengths.

One object of this invention is to provide novel chemical compounds and processes for the preparation of same.

Another object of this invention is to provide novel intermediates for said novel compounds.

Still another object of the invention is to provide novel photospirans which, in the open form, are chelatable with metal ions.

Other objects of the invention will in partbe obvious andwill in part appear hereinafter.

The invention accordingly comprises the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description.

It is known that certain classes of compounds undergo a ptotochemical change upon exposure to radiant energy whreby the color characteristics of the compound are temporarily altered. Such compounds are known as phototropic compounds when the color characteristics are affected by light, e.g., visible or ultraviolet light, and'as thermochromic compounds when the color characteristics are affected by heat. The compounds with which the pres ent invention is concerned are photospirans.

It is believed that the color change in phototropic materials is produced by the isomeric modifications of the compound. Generally, when the influence of the radiation is removed, the compound is restored to its original condition. Photospirans generally exist in the normal or stable state in what is known as the closed form. Under the influence of the aforementioned radiation, they change to the open form and assume a color different from that of the closed form. The open form. generally appears to be an unstable form and the ring closes upon the removal of the radiant energy.

The novel compounds of this invention are materials which will undergo photochelation; that is, theyare phototropic compounds, which, in the open or colored form, will chelate with a metal ion thereby forming aspecies which will not revert to the original, closed form. The novel compounds of this invention are compounds which; will not chelate with metal ions in the closed form, which is generally the colorless form but will chelate in the open form.

The novel chelatable photospirans of this invention in the open form have a substituent ortho to the Le, in the 8 position. As examples of suitable substituents, mention may be made of:

p, nited States Patent 0 3,299,079 Patented Jan. 17, 1967 "ice wherein R may be alkyl or aryl, R may be hydrogen, alkyl or aryl and each of two Rs together may be a divalent aliphatic radical, =e.g., a pentamethylene radical completing, with the nitrogen atom, a piperidine ring. The radicals represented by R and R may contain watersolubilizling groups, thereby imparting water-solubility to the photospiran. The preferred radicals represented by R and R are lower alkyl such as methyl and ethyl and aryl such as phenyl. It should 'be understood that the size or composition of R or R is not critical in the preparation of photospirans within the scope of this invention, however, it should be understood that the radicals contemplated by R or R should not have the eifect of rendering the compounds non-phototropic or non-thermochromic by, for example, steric hindrance.

The novel photospirans of the present invention may be represented by the formula:

wherein X is the residue of a methylene base and Y is a radical capable of chelating with a metal ion when Compound A is in the open form.

The term residue of a methylene 'base, as used herein, is intended to refer to the methylene base portion of the compound after condensation of said methylene base with the particular salicylaldehyde to form the photospiran. The term X may also be defined as the atoms necessary to make up a methylene base after said methylene base has been condensed with the particular salicylaldehyde.

As examples of suitable methylene bases which may be used in preparing the novel compound of this invention, mention may be made of:

The numbering scheme of the ring positions of the novel compounds is illustrated by reference to a wellknown photospiran, 1,3,3-trimethyl 6'-nitro-spiro-(2- H, 1-benzopyran-2,2.-indoline) This scheme of substitutent identification will be adhered to throughout this application.

Photospirans are transformed from the uncolored form to a colored form, or from one color to a different color, by the action of heat and/ or exposure to a particular Wavelength of radiation, generally ultraviolet radiation. In the past, if permanence of the color of the open species was desired or if the susceptibility of the compound to the action of heat or light was desired to be lessened or eliminated, it was necessary to remove the solvent to produce the solid form of the spiran. By means of the present invention, a stable form of the photospiran can be achieved easily and readily by the addition of a metal ion to the open form of the photospiran.

As examples of photospirans within the scope of this invention, mention may be made of the following:

(1) CH3 CH3 N/ O N02 on; oH=N- (2) CH3 CH3 N O NO:

| CH3 CHz-()CHr-CH (3) CH3 CH3 1 CH CHzN CH3 CH3 N/ O- NO:

C 3 CH2OH The novel photospirans of the present invention are transformed from the closed to the open form by the influence of heat or ultraviolet light or light which comprises the blue portion of the spectrum.

The novel compounds of this invention exhibit phototropism when dissolved in certain solvents, such as benzene, toluene, chlorinated hydrocarbons, and chlorinated biphenyls; where the particular metal salt used to provide the chelating metal ion is soluble in the same solvent, the compounds of this invention may be chelated in solution. In certain instances where the metal salt would not ordinarily be soluble in the selected solvent, e.g., benzene, it is possible to render the salt soluble by adding minor amounts of certain polar solvents, such as ethanol, without affecting the phototropic behavior of the photospirans.

In certain polar solvents in which the photospirans of this invention are soluble, the compounds may exhibit a tendency to be converted to the open form almost immediately upon being dissolved therein, without any activating energy such as light or even heat. This phenomenon is believed to be due primarily to the action of the particular solvent upon the photospiran, particularly in view of the fact that so long as the compound remains dissolved in such a solvent, it cannot be reconverted to the closed form by any change in physical conditions such as changes in light or heat surroundings.

salicylaldehyde.

the particular solvent is removed, e.g., by evaporation or by precipitation of the photospiran into selected nonsolvents, they immediately revert to the closed form unless treated with some activating energy.

In accordance with this invention, if metal ions are added to solutions of the aforementioned type, chelate formation takes place substantially as in solvents in which the compounds do not open without external activating energy. Thus, when the solvent is removed, the photospirans remain fixed in the open position by virtue of the chelate formation, irrespective of changes in external physical conditions.

In general, it is believed that the ability of the novel photospirans of this invention to form stable chelates in solution is due, at least in part, to the strong stability constant of the particular chelatable group in the 8' position. It should be noted that the solvent should be seleeted with due regard to the solubility of the metal ion. The molar ratio of photospiran to metal ion is preferably at least 1 to 1.

In addition to being phototropic in solution, the compounds of this invention exhibit phototropism when dispersed in certain colloidal or polymeric films, such as polyvinyl alcohol, polyvinyl pyridine, polystyrene, cellulose acetate, and the like. In these instances, the compounds can be fixed in the open form by chelation in a manner analogous to that of solvent-chelation. The compound of Formula 2 has also been found to be phototropic in theanhydrous crystalline form, going from yellow to orange upon exposure to activating energy.

The novel compounds of the present invention may also exhibit thermochromism and chelate in the solid form, e.g.-, by'melting together a photospiran and a compound which will provide the necessary metal ion.

The compounds of the present invention are chelatable by ions of metals of the transitional series, particularly coDDer, cobalt, nickel, zinc and chromium.

The novel compounds of the present invention may be prepared by reacting a methylene base with a 3-substituted salicylaldehyde of the formula:

(B) OH CHO radical wherein R is an alkyl or aryl radical and R is hydrogen or an alkyl or aryl radical. The novel compounds of this invention may also be prepared by reacting a methylene base with a Schiff base of a 3-substituted The Schiff base of a 3-substituted salicylaldehyde may be defined as the condensation product .of a salicylaldehyde and a primary amine of the formula:

R-NH wherein R has the same meaning as above, and may be represented by the formula:

The compounds within Formula B wherein Y is a -CH=O, CH -O--R CH2NR or a CH=NR radical may be prepared directly from 3-chloromethyl-S-nitrosalicylaldehyde.

When Y is -CH=O, the compound of Formula B may be prepared by oxidizing 3-chloromethyl-S-nitrosalicylaldehyde with dimethylsulfoxide.

When Yis OHz-1 I-R theicompound of Formula B may be prepared by reactingL3-chloromethyl-S-nitrosalicylaldehyde with a second ary amine.

The 3-substituted salicylaldehydes may be prepared with amineslof any size and are limited only by the effect they may have on the finished spiran as a result of steric hindrance. As examples of suitable amines which may be used to form the compounds with Formula B when Y acting 3-chloromethyl-5-nitrosalicylaldehyde with an alcohol. As examples of alcohols suitable for use in the present invention, mention may be made of the following:

CHaOH OH CHgOH (CHmCHOH omonzonzornon When Y is N=NR, the compound of Formula B may be prepared by coupling a diazonium salt into 5- nitrosalicylaldehyde.

When Y is CH=NR, the compound within Formula C may be prepared by oxidizing 3-chloromethyl-5- nitrosalicylaldehyde with dimethyl sulfoxide and reacting the product with two moles of a primary amine, R--NH As examples of suitable amines, mention may be made of the following:

CHaNHz C H3O 112N112 Ha)zCHNHz The substituted salicylaldehydes and Schiif bases of salicylaldehydes are preferably prepared from 3-chloro- 'methyl 5-nitrosalicylaldehyde.

3-chlorornethyl-S-nitrosalicylaldehyde may be prepared by reacting 5-nitrosalicylaldehyde with chlorornethyl methyl ether and aluminum chloride. 3-chloromethyl-5- nitrosalicylaldehyde and" the preparation thereof is disclosed and claimed in the copending application of Lloyd D. Taylor and Robert Davis, Serial No. 220,035, filed August 28, 1962.

The following nonlimiting example illustrates the preparation of the 3-chlorornethyl-5-nitrosalicylaldehyde starting material. i 1

Example A A 2-liter, 3-necked round bottom flask was fitted with a mechanical stirrer, addition tube and an Allihn condenser surmounted with a'Friedrichs condenser fitted with a calcium chloride drying tube. Into the flask was placed 95 gm. (0.57 mole) of 5-nitrosalicylaldehyde and 1 liter of chloromethyl methyl ether. The solution was cooled to about 5 C. 332 gm. of aluminum chloride was added with stirring over a one hour period. The thus-formed slurry was slowly brought to room temperature and then to reflux. Reflux was continued until the evolution of hydrogen chloride ceased. The remaining viscous solution was cooledto room temperature and poured with stirring into 3 liters of crushed ice. The resulting brown tar was stirred with ice water for approximately 30 minutes. The'p r oduct, a brown solid, was then filtered and washed with water. The filtrate was twice extracted with ether. The ether extract was dried with sodium sulfate and the ether removed by evaporation. The resulting brown solid was added to the product. The product was further purified by recrystallization from carbon tetrachloride and hexane. 108 gm. of 3-chl0romethyl-5-nitrosalicylaldehyde was obtained melting at 90.5-91.5 C. and showing the following analysis for C H ClNO Calculated: C, 44.58; H, 2.81; N, 6.50; Cl, 16.45. Found: C, 44.4; H, 2.8; N, 6.6; Cl, 16.7.

Example B The photospiran j/CD was prepared in the following manner. In a 500 ml. beaker, 25 gm. of 3-chloromethyl-5-nitrosalicy1aldehyde was dissolved in 200 cc. of dry ethanol. Water was added to a cloud point at approximately C. The solution was allowed to cool and white needles were formed. The compound:

CH: CH3

N l 3 3H3 CHr-N was prepared in the following manner. To a solution of 2.15 gm. (0.1 mole) of 3-chloromethyl-5-nitrosalicylaldehyde in 2 litersof dry benzene was added 17.0 gm.

(0.2 mole) of piperidine. The resulting precipitate was removed by filtering and dissolved in 1 liter of water and sufiicient hydrochloric acid to dissolve the precipitate. The solution was neutralized with sodium hydroxide. The product, 3,N-piperidinomethyl-S-nitrosalicylaldehyde, was filtered and dried, decomposes at about 235 C. and showed the following analysis for C H N 'O Calculated: C, 59.1; N, 6.1; H, 10.6. Found: C, 58.9; N, 6.1; H, 10.7. It is believed that 3-N-piperidinomethyl-S-nitrosal-icylaldehyde exists as a Zwitterion in both the solid and in solution.

A solution containing 400 cc. of absolute ethanol, 5.19 (0.03 mole) of Z-methylene-1,3,3-trimethylindoline and 7.92 (0.03 mole) of 3,N-piperidinomethyl-S-nitrosalicylaldehyde was refluxed for 16 hours. The solution was filtered and the, filtrate allowed to crystallize. -The prodnot was filtered and redissolved in 500 cc. of absolute ethanol and recrystallized. The photospiran melted at 148 C. and showed the following analysis for C H N O Calculated: C, 71.6; N, 10.0; H, 6.9. Found: 71.6; N, 10.1; H, 7.0.

Example D The photospiran CH CH was prepared in the following manner. To a boiling solution of 7.30 gm. (0.034 mole) of 3-chloromethyl-5-nitrosalicylaldehyde in 50 ml. of acetone, 50 ml. of distilled water was added. The solution was then heated for 15 minutes. Upon cooling, white needles separated out which were removed by filtration and dried. The product 3-hydroxyme-thyl-S-nitrosal-icylaldehyde, melted at 135- 136 C. and showed the following analysis for C H NO Calculated: C, 48.7; H, 3.55; N, 7.1. Found: C, 48.9; H, 3.7; N, 7.0.

Into a 100 ml. round bottom flask, fitted with a reflux condenser and a calcium chloride drying tube were placed 1.0 gm. of 3-hydroxymethyl-S-nitrosalicylaldehyde and 50 ml. of absolute ethanol. One equivalent of 2-methylene1,3,3-trimethylindoline was added to the flask and the solution was refluxed overnight. The ethanol was then evaporated and 50 ml. of dry hexane was added. A purple solid precipitated. The production was recrystallized three times from acetone and water. The photospiran melted at 187-188 C. and showed the following analysis for C H N O Calculated: C, 68.2; H, 5.68; N, 7.95. Found: C, 68.2; H, 5.7; N, 7.9.

The phototropic properties of the novel compounds of the present invention were determined by exposing a solution of the photospiran in benzene, acetone, or ethanol to a source of ultraviolet light and observing the color change. Upon removal from exposure of the ultraviolet light, the photospiran slowly reverts to its original color, indicating the change from the open to the closed form.

The chelation of the photospirans was examined by mixing together a solution of the photospiran and a metal ion in a solvent in which the photospiran in both open and closed form, the metal ion, and the photospiran the samples, for the reason that the precipitated chelate in each case differed in color from the precipitated spiran in the closed form.

The following nonlimiting examples illustrate the chelation of the photospirans of the present invention:

Example E A 1 to 1 mole ratio of and cobaltous chloride were dissolved in a 9 to 1 benzene/ethanol solution, forming a deep blue color. The solution was then divided into 3 portions and handled in the following manner: (1) The first portion of the solu tion, after standing at room temperature for a few minutes, was poured into an excess of aqueous acetone where the photospiran precipitated in its noncolored closed form. (2) The second portion of the solution was exposed to a source of ultraviolet radication for 2 minutes whereupon it turned red in color. The solution was then poured into an excess of aqueous acetone forming a precipitate red in color indicating the chelation of the photospiran in its open form. (3) The third portion of the solution was exposed to heat at C. for 2 minutes and produced the same effects as noted in 2) above.

Example F 0.1 gm. of the photospiran employed in Example E was dissolved in a 1 to l ethanol/acetone solution. Virtually instantaneously, a purple color appeared. The solution was then divided into 3 portions and handled in the following manner: (1) The first portion of the solution was poured into an excess of water, where the photospiran precipitated, predominantly in its noncolored form. (2) The second portion was exposed to a source of ultraviolet light for 2 minutes; no further color change was observed, indicating that the photospiran was already in its open form. The solution was then poured into an excess of water, where again, the photospiran precipitated, predominantly in its noncolored form. (3) To the third portion was added an equimolar quantity of cobaltous chloride, the color of the solution was observed to change from purple to orange-brown, owing to the fact that the color of the cobalt chelate in this instance differs from that of the open but unchelated photospiran. This solution was then poured into an excess of water, resulting in a red-colored precipitate.

Two controls were also observed in conjunction with the foregoing chelation experiments. The first comprised a solution of the above-noted photospiran in the benzene/ethanol solution which turns blue-purple upon exposure to ultraviolet light and colorless when allowed to remain in the dark overnight, and also when precipitated in water. The second control comprised a benzene/ethanol solution of cobaltous chloride which is deep blue in color and which diminishes in intensity of blue color when poured into water solution.

Similar results were obtained using the other photospirans of Examples E and F using nickel chloride and zinc acetate as Well as cobaltous chloride.

9 Example G A 1 to 1 mole ratio of and cobaltous chloride were dissolved in a 9 to 1 benzene/ethanol solution, forming a pale orange color. The solution was then divided into 3 portions and handled in the following manner: (1) The first portion of the solution, after standing at room temperature for a few minutes, was poured into an excess of water, where the photospiran precipitated in its noncolored closed form. (2) The second portion of the solution was exposed to a source of ultraviolet radiation whereupon it turned orange in color. The solution was then poured into an excess of water forming a precipitate red in color, indicating the chelation of the photospiran in its open form. (3) The third portion of the solution was exposed to heat at 80 C. for2 minutes, and produced the same effects as noted in (2);

Example H A l to 1 mole ratio of the photospiran used in the foregoing example and cobaltous chloride were dissolved in an ethanol/acetone solution. The resulting green solution was then divided into 3 portions: (1) The first portion was observed at room temperature and the green Upon pouring the solution (2) The secnd portion was exposed to ultraviolet light for 2 minutes.

The solution turned brown in color and formed a magenta precipitate in water. (3) The third portion was subjected to heat and reacted in the same manner as the solution exposed to ultraviolet light. A control sample showed the photospiran to be colorless in water. The intensity of the color and speed with which it forms in the room temperature experiment indicates a slower rate of activation at room temperature than with ultraviolet light or heat.

By way of control for the two foregoing experiments, the photospiran employed therein was dissolved in a 9 to 1 benzene/ethanol solution. Upon exposure to ultraviolet:light, the solution became purple in color. When allowed to remain in the dark overnight, it reverted to a substantially colorless form; when poured into an excess of water, a colorless precipitate resulted.

The novel chelatable photospirans of the present invention may be used in heatand light-actuated document copy processes and in sensitizing record materials.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter 10 contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is: 1. A photospiran, chelatable in the open form, of the formula 3. A compound of the formula 4. A compound of the formula C H: C H:

O NO: T

C H OH 0 H; T-

No references cited.

ALEX MAZEL, Primary Examiner.

M. OBRIEN, Assistant Examiner. 

1. A PHOTOSPIRAN, CHELATABLE IN THE OPEN FORM, OF THE FORMULA
 3. A COMPOUND OF THE FORMULA 